62 DT7BLIN NATURAL HISTORY SOCIETY. 



relations of the fruitful ♦•branch," as it is called, in this plant. Strikingly it dif- 

 fers from the linear outline of the ordinary form, with its simple pinnae and fla- 

 belliform venation, whilst this form has a deltoid outline, and the lower pinnae 

 decompounded, with pinnatifid pinnules, and a distinct mid-rib, and secondary 

 venation springing therefrom, being exactly the converse of the variety of Blech- 

 nura spicant, which I exhibited before you, under the name of dissectum (Kin.), 

 and which Francis first described as Strictura, in which we found the ordinary 

 linear pinnules of that fern reduced to simple pinnate lobes, and the venation, 

 instead of being made up of secondary veins springing from a [median axis, re- 

 duced to the flabelliform arrangement, which is the normal arrangement in Bo- 

 trychium. But it is in the second point I think its chief interest consists ; for, 

 taking this form in connexion with two other abnormal forms — viz., that in 

 which we find the pinnae deeply incised at their edges, and that in which we find 

 many of the pinnae soriferous at their edges — we are led to believe that these two 

 portions of the ordinary plant of Botrychiura, generally called branches, really 

 represent the two surfaces of an ordinary dorsiferous fern, only that in one the 

 venations take on the flabelliform, and in the other the branched form ; for, ex- 

 amine those fronds whose pinnae are soriferous at their edges, and we see the 

 nerves coalescing, and forming a sort of a mid-rib to the division of the pinnae, 

 on whose termination the sorus is placed ; nearly the same arrangement as we 

 find in the deltoid form just described, where we find the nerves uniting and form- 

 ing a common mid-rib, on whose sides the secondary divisions of the pinnae are 

 placed. Going a little farther — this may lead us to believe that the form of 

 Ophioglossum vulgatum, where we find two leafy fronds developed instead of 

 one leafy and one fertile frond, are really only plants whose fertile element, from 

 some reason or another, is not fully developed, but remains as a barren frond. 

 That this is the correct explanation of the change, is shown in one specimen, in 

 ■which one half of the frond is normal, the other of the deltoid type ; and also in 

 Blechnum spicant, where, even in the same frond, we see parts in which the 

 usual linear pinnae are preserved, and others in which this, if I may call it so, 

 flabelliform type is well shown; while, by comparing the common form with this 

 variety, the interchange of the two types is well seen. 



In conclusion, 1 have the pleasure of recording a new Irish habitat for Wi- 

 thering's Fern (Lophodium spinosum, Newm.), which I met with, in some quan- 

 tity, on the edges of the bog drains in Annagh Inch, parish of Dorrha, county of 

 Tipperary. Its occurrence as Irish has been previously made known by Lovat 

 Darby, Esq., in the county of Monaghan. — [Vide Proceedings, antey pp. 15, 25.] 



MARCH 10, 1854. 



Dr. Kinahan exhibited a plant of Scol. vulgare (var. marginatum), found by 

 him at Tinnohiuch, county of Wicklow, March 2, 1854, its first record as Irish. 

 This variety (first discovered in England by Sir W. C. Trevelyan) is remark- 

 able for having the epidermis on the back of the frond raised into a membra- 

 nous ridge or tuck, running in a wavy line along it, at some little distance from 

 the edge of the frond ; the fronds are scolloped and serrated along the edges, 

 the sori either continuous over the ridge to the edge of the frond, or stopping 

 at it, when we find a second set of sori arising outside the hem ; or, thirdly, the 

 sori are only produced external to the hem. The form is further remarkable for 

 having several modifications — firstly, that under consideration ; secondly, a form 

 named bimarginatum, in which there is a hem on both faces of the frond ; 

 thirdly, a form named supralineum, where the hem exists only on the upper sur- 

 face of the frond ; and, fourthly, in a form named dubium by its discoverer, G. 

 B. Wollaston, Esq., by whom it was raised from seed, in which we find the free 

 margin running along a frond with multifid apices. In all these forms we find an 

 irregularly serrated margin to the fronds, showing that probably the deficiency 

 of the substance at the edge of the frond and of the epidermis, or, taking ano- 

 Iher view of the case, the irregular growth of the epidermis and of the venules 

 and apices, proceed from the same cause. 



